Telephone subset



April 1942' E. s. McLARN I 2,

TELEPHONE SUBSET Filed Oct; 29, 1938 4 Sheets-Sheet l Fi ll [Milli INVENTOR ERNEST s. -M-'LARN v BY 16 v W 15 ATTORNEY April 14, 1942. A a. s. McLARN TELEPHONE SUBSET Filed Oct. 29, 1938 4 She ets-Sheet 2 FIG-.4.

INVENTOR ERNEST s. M LARN ATTORNEY 2 April 14, 1942. E. s. McLARN 2,279,713

TELEPHONE SUBSET Filed Oct. 29, 1938 4 Sheets-Sheet 4 FIG.6.

SPEC/14L [MI/08E 7' CONTAIN/M9 DIAL CONVE/VT/0/VAL LINE W TERM/ML 'ro sauce/e553 LINE T0 LINE T0 LINE INVENTOR ERNEST s. mun/v BY ATTORNEY Patented Apr. 14, 1942 UNITED STATES PATENT OFFICE TELEPHONE SUBSET Ernest S. McLarn, Manhasset, N. Y., assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application October 29, 1938, Serial No. 237,696

7 Claims.

unit of equipment and electrically connected to form a whole or a part ofa subscribers substation equipment.

It is an object of theinvention to provide a subset composed of a number of separate elements each of which can be readily made accessible for inspection or repair and also can be readily removed and replaced by a corresponding new ele-- ment to repair the subset. It is an especial object of the invention to provide such a subset in v which all the circuit elements, or at least the most important ones thereof, may be rendered accessible for inspection and testing without dis-- associating such elements from one another mechanically or electrically, thus enabling the set to be inspected and tested whil still maintain.- ing the cooperative electrical and mechanical relationship of at least the most important parts thereof.

It is another object to provide such a subset in which the electrical interconnection of the variout parts is effected by the cooperation of a, rigid interconnecting structure with which rigid terminal members of the difierent component elements are adapted to engage.

It is a further object of the invention to provide a subset mechanism unit which shall be capable of being adjusted for operation in a plurality of different positions, and especially to provide such a subset mechanism unit which by the addition of different types of housings, and in some cases of a very few other parts, is adapted to constitute either a complete wall type subset or a desk type subset, but in which each type of subset shall nevertheless have desirable external proportion and a pleasing and suitable shape. Other objects of the invention will appear from the following description together with the appended claims.

In accordance with one feature of the invention the subset mechanism unit is adjustable for use in either a vertical or a horizontal position and two different types of housings or cover members are provided, either of which may be as-' sembled with such unit to constitute a complete subset, which is thus optionally either of the wall type or of the desk type depending upon the form of housing or cover employed. According to another feature of the invention such a universal subset mechanism, which is adapted for use with different housings, comprises an adjustable cradle switch mechanism supported independently of the cover or housing member but cooperating with a cradle which is formed integrally with or attached to the cover or housing member. This feature permits the cradle design to be accommodated to the shape of the housing member so as to result in a pleasing and suitable overall appearance of the subset while still providing the important advantages of a cradle mechanism which is independent of the cover.

Another important feature of the present invention is the provision of a self-contained subset mechanism comprising all the essential electrically and mechanically cooperating parts of the subset, which is so constructed that all the elements thereof which require protection are selfprotected from dust and the like independently of the cover.

The invention may best be understood from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a side elevation partly-in section of a desk type subset embodying the present invention;

Fig. 2 is an oblique-view of the dial bracket of the subset of Fig. 1, taken perpendicular to the face of the dial;

Fig. 3 is a sectional view of the cradle-switch mechanism taken along line 3-3 of Fig. 1;

Fig. 4 is a plan section along line 4-4 of Fig. 1;

Fig. 5 is a side elevation of a wall type subset incorporating the same subset mechanism unit as that of Figs. 1, 2, 3 and 4;

Fig. 6 is a bottom view of the terminal block incorporated in the subsets of Figs. 1, 2, 3, 4 and 5, together with schematic representations of the cooperating circuit elements; a

Fig. 7 is a schematic representation of a special handset for use with either the subset of Figs. 1. 2, 3 and 4 or that of Fig. 5;

Fig. 8 is a diagram of a substation circuit obtainable with the terminal block of Fig. 6;

Figs. 9 and 10 are similar diagrams of modified substation circuits obtainablewith the terminal block of Fig. 6;

Fig. 11 is a bottom view of a modified terminal block which may be substituted for the terminal block of Fig. 6; r

Fig. 12 is a diagram of a circuit resulting from the use of this modified terminal block of Fig. 11.

Referring more particularly to Figs. 1, 2, 3 and 4, which represent one embodiment of a desk 2 arrears ,type subset in accordance with the present invention, upon a base i are mounted a condenser 2, a ringer 3, an induction coil 4, a terminal block 3 and a cradle-switch mechanism bracket 6. The condenser 2 and the induction coil 4 are preferably of the type described in my copending U. S. Patent application No. 181,493, filed December 24, 1937, having molded cases of phenol condensation product or the like within which the electrical elements themselves are potted hermetically with suitable potting compounds. The ringer 31s of somewhat similar construction, but certain parts of this ringer which should be free from potting compound are covered with a dust-proof cover as shown in Figs. 13 and 14 and as more particularly described hereafter. Each of these three electrical elements, the condenser, the ringer and the induction coil has two or more terminals I which engage eight corresponding terminals 0. b, I, 0. h of terminal block 5 (best seen in Fig. 6) being clamped against these terminals by the corresponding terminal screws to, lb, 30, la, 2e, 3!, 3a and 3h as shown in Fig. 4.

The cradle-switch mechanism bracket 3 carries the plunger block 2 which is generally of truncated, rectangular, pyramidal shape, but which has an exteriorally cylindrical projection I0 as best shown in Figs. 1 and 3. This block 3 is rotatably supported by engagement of its portion II with a corresponding circular opening in bracket 6, being retained in place by snap ring II. A roughly T-shaped plunger I2 is slldably fitted within the corresponding T-shaped cavity i3 in block 9 and is pressed outwardly by coil spring l4, but limited in its outward motion by engagement of its enlarged head IS with split disc It as shown in Figs. 1 and 3. The lower surface of the enlarged head i5 is conical, preferably having an apex angle of about 90. Thus,

whether the mechanism is in the position shown in Fig. 1 or in the alternate position shown in Fig. 5, the head I! is invariably adapted to exert pressure in the same direction against cooperating roller ll of spring nest ii. If desired a look. ing catch may be provided for holding block 9 in one or the other of its alternate positions although this is not essential where the subset cover will serve to maintain block 9 in position.

The spring nest I3 with whose roller ii the cradle mechanism cooperates as above mentioned, comprises an inverted L-shaped molded frame l9 forming one side wall and a top for the spring nest, and a T-shaped base portion 20 molded integral with the frame is. A set of five contact springs 21, 22, 23, 24 and 25 are disposed within the L-shaped frame l9, and have their lower ends imbedded in the base portion 20 of this frame. Lugs 2 I a, 22a, 23a, 24a, and 25a integral- 1y formed at the lower ends of the respective springs 2l-25 extend out through the bottom of the base portion 23 of the frame I! as shown in Fig. 1, these lugs being preferably staggered as more clearly shown in Fig. 6. A further spring 26 merely serving for transmitting mechanical motion is likewise imbedded in the base 20 and extends up outside of the inverted L- shaped frame is. The top extremity of this pusher spring 26 carries a roller l'l previously mentioned, which cooperates with the cradle plunger i2. A pusherstud 21 extends through frame i9, its ends being respectively in contact with the pusher spring 26 and the contact spring 22. A further stud 28 is riveted to contact spring 22 and bears against contact spring 24 as shown in Figs. 1 and 2. Thus whengthe spring nest is and the cradle mechanism are mounted in cooperative relation as shown inFig. 1, the depression of the cradle plunger i2 causes the conical head II of this plunger to move the roller II to the right, as a result of which pusher spring 23 presses on stud 21 to move contact spring 22 to the right. Furthermore; through the agency of stud 23 contact spring 24 is likewise moved to the right. Thus the depression of the cradle plunger l 2 results in breaking the contact between springs 2| and 22 and breaking the contact between springs 23 and 24 while making a contact between springs 24 and 23.

In order to render the spring nest dust-proof and insect-proof independent of the housing of the entire subset, a U-shaped transparent cover 29, preferably of cellulose acetate, is slipped around frame I! as shown. This cover together with the design whereby the springs are actuated through the wall of the frame I! by stub 21, serves to protect the spring nest from dust and insects and thus greatly reduces the occurrence of contact failure.

The entire spring nest i3 is attached to terminal block 3 by screws 34 which extend through the base portion 20 into block 5. The terminal lugs Has-43a of the spring nest which project below the base portion 20 as shown in Fig. 1, extend into corresponding holes in the terminal block, being of such length as to almost reach the lower surface 3| of the terminal block I as shown in Fig. 1. A number of grooves 32 are formed in the lower surface 3| of the terminal block as shown in Fig. 6. Preferably the terminal block is molded of some suitable plastic having mechanical strength and insulating properties such as a phenol condensation product,

and in such case the grooves 32 may be formed by molding. Five of these grooves are formed with enlarged ends and are positioned so that these enlarged ends surround the lugs 2ia--25a of the spring nest when the spring nest is fixed in proper position on the terminal block. Other enlarged ends of these grooves 32 are positioned to surround the lowest extremity of terminal studs 0, b, c, d, e, f, g and it previously mentioned, to which the ringer, condenser and induction coil are connected. Four further terminal studs m, n, p and q are provided for cooperation with the dial cord later to be described, and three more studs i, j and k-may also be provided although these are not essential. Preferably the terminal studs i, d, k, m, n, p and q are of similar form to the previously described terminal studs 0, b, c, d, e, f, g and It, all these studs being sufilciently large at their top end to permit drilling and tap-;

ping for terminal screws such as the previously mentioned screws I, and being preferably of smaller diameter at their lower ends as shown in Fig. 6 in order to provide long leakage paths on the bottom of the terminal block 3.

In addition to these terminal studs 41, b, c, d, e, j, g, h, i, j, k, m, n, p and q, six additional terminal punchings r, s, t, u, v and w are provided in the terminal block as shown-in Figs. 1 and 6. The upper ends of these punchings are preferably of saw-toothed form and sharpened as shown in Fig. 1, the lower ends of these punch ings being preferably small projections staggered as shown in Fig. 8. The lower ends of these punchings r-w, as well as the lower ends of the terminal studs a-.-q are of such length as to surface 3! of the block I.

The various grooves in the lower surface ll of the block 6 have enlarged end portions and intermediate portions as shown which surround the terminal punchings and terminal studs in the same manner as described for the terminal lugs 2la-2ia of the spring nest, these grooves being arranged in substantially the pattern shown in Fig. 6 and being preferably shaped so as to provide the maximum leakage paths between grooves at all points. These grooves are filled with conducting material such as solder or other low melting alloys, e. g. by a spraying process, while the terminal punchings, terminal studs and terminal lugs of the spring nest are in position.

In order to supplement the connections formed by the metal in grooves 32 a four-conductor dial cord is provided internally of the subset and two three-conductor cords are provided externally of the subset, one extending to the terminal block and one to the handset containing the transmitter and receiver.

The dial cord 33 is a four-conductor rubber covered cord of fiat form equipped at one end with four spade terminals shaped to fit the screw terminals of a conventional dial, and at the other end with four spade terminals of larger size adapted to fit under screws 34m, Mn, 34p and se which screw into the top of terminal studs m, n, p and q respectively. At the end of the dial cord which cooperates with the terminal block the rubber insulation is preferably cut away diagonally and the individual conductors bearing the spade tips are made very short so that it is almost impossible to connect these spade tips to the studs m, n, p and q in an incorrect fashion. Similarly at the dial end of the cord the leads extending to the ends of the spade tips are made as short as possible to render it difficult to connect these spade tips improperly. The dial cord extends from the terminal studs m, n, p and q upward along the underside of bracket 6, being disposed in a channel 35 formed on the underside of this bracket and being retained in position by retaining clips not shown. At the top of the bracket 6 the dial cord passes over a bolt 36 as more clearly shown in Figs. 1, 2 and 5, and then extends to the dial through an opening in the dial mounting bracket later to be described.

The 'extemal cords 31 and 38 are preferably also of the parallel conductor type with rubber insulation like the dial cord, but these cords each carry three conductors instead of four and preferably are made not quite fiat but rather of an asymmetric shape to prevent improper positioning of these cords. The cord 38 is connected at one end to a handset of conventional type which in itself forms no part of the present invention.

'I'he opposite end of this cord 36 is placed in a groove 38 in terminal block so as to rest on the and caused to be pierced by the punchings by screwing down clamping member 42 by means of screws 43. The free end-of cord 311s connected to a conventional three-terminal terminal block to which are brought the incoming subscribers' lines and the earth connection if one is required.

The complete apparatus described up to this point constitutes a subset-mechanism unit of universal application which may be used either in a desk type subset such as shown in Figs. 1 and 4,

or in a wall type subset such as shown in Fig. 5. Furthermore, by the omission of the dial and the dial cord this same subset mechanism may be used in inanual telephone systems merely by strapping together terminal studs m and p. Furthermore, diflerent circuit modifications may be made to accommodate different ringing systems without changing the design of the .terminal block in any respect. Also the special type of handset disclosed in my copending U. S. Patent application No. 138,492, filed April 28, 1937, and containing a dial positioned around the transmitter of the handset may be substituted for a conventional handset merely by omitting the dial and dial cord and strapping together terminal studs m and p as for manual operation.

The only portions of the complete subset which are diiferent for subsets of the wall type and desk type are the housings or covers 65 and 66 respectively, as shown in Figs.'1 and 5, and the dial brackets 61 and 66 respectively, as shown also in Figs. 1 and 5. The housings 65 and 66 are entirely diiferent in shape and general appearance as clearly shown by a comparison of Figs. 1 and 5. Each of these housings, however, comprises merely a single molded member preferably of insulating plastic, e. g. Bakelite or other phenolic condensation product, but if desired of metal. The housings may also be made by stamping if desired, but in such case the cradle portion of the housing would preferably be aflixed separately. For reasons of appearance and texture, however, it is ordinarily preferable to employ a molded non-metallic housing.

The dial supporting bracket 61 is preferably a single casting of suitable elastic metal having a hollow generally drum-shaped body 14, a pair of upper legs 10 and a pair of springy lower legs 69 having pivot projections 1| thereon. The bracket is pivotally supported by its upper legs 16 from the bolt 36 at the top of bracket 6, and

sharpened saw-toothed terminal punchings t, s

and r. A clamping member 46 is then placed on top of the cord and screwed down with screws 4| so as to force the cord completely into the groove 39 and cause it to be' pierced by the terminal punchings t, s and 1-. It will be noted that the opening formed by clamping member 46 together with screw 39 is of asymmetric shape to correspond with the asymmetric shape of the cord 38, thus making it impossible or difllcult to screw the clamping member 46 completely down if the cord is not correctly positioned. In similar manner the cord 31 is placed in another similar groove not shown, into which the punchings u, v and w project, and is forced into this groove normally the lower legs 69 of the dialbracket are engaged with lugs 15 on the base plate I, thus holding the dial bracket fixedly in position. When it is desired to inspect the portions of the subset lying beneath the dial, however, this may v be readily thrown up out at the way merely by grasping the two lower legs 69 and pressing them together so as to disengage the pivot projections 1| from the lugs 15.

The dial bracket 68 shown in Fig. 5 which is used in the wall-type subset is essentially similar to the dial bracket 61 above described, except that the lower legs 12 are somewhat longer so as If desired, both the dial brackets 61 and 63 may be fitted with removable transparent cover plates on the underside thereof to protect the dial mechanism from dust while yet rendering it readily visible and accessible when thev dial bracket is swung upwardly without requiring removal of the dial from the dial bracket.

In Fig. 6 the electrical relationship between the terminal block I and the other cooperating electrical elements of the substation circuits are schematically shown, for a substation in an automatic system using a conventional handset and a conventional dial and arranged for'loop ringing. Fig. 8 schematically represents the resulting substation circuit. If two-party selective ringing of the type conventionally employed in the so-called European rotary system is desired, the subset for the first party is modified by removing the strap between terminal studs b and c and the strap between the earth terminal and one line terminal of the terminal block shown in Fig. 6. The center terminal of the terminal block is then connected to a suitable earth connection. At the substation of the second party on the selective ringing line the terminal block strap is similarly removed and the center terminal of the terminal block is grounded, but the strap between terminals b and c remains in position. Figs. 9 and 10 respectively show the resulting circuit for the substation of the first and second party. It will be understood that terminal u in the second party's substation is connected to the same sideof the line to which terminal w at the party's substation is connected and vice versa.

For some purposes it may be preferred to employ the substation circuit schematically shown in Fig. 12 instead of that shown in Fig. 8. The circuit arrangement represented in Fig. 12 may be realized by substituting the modified terminal block 5 of Fig. 11 for the terminal block 5. When the special handset containing a dial, and wired as shown in Fig. 'l issubstituted for the conven- 1 tional handset in the system having the special terminal block shown in Fig. 11, however, the

resulting schematic circuit will no longer be that in Fig. 6 may be used in a magneto local battery telephone set. In this system the magneto should be furnished with suitable internal wiring in which two contact springs and a transfer spring are used. The necessary connection may best be seen by reference to Fig. 4. The contact spring which is closed in the normal, idleposition is connected by a conductor under screw If, the transfer spring is connected by a conductor clamped under screw lie. The other contact spring is connected to the magneto armature winding, the other side of the winding being connected to a conductor clamped under screw 81). A connection is made between 8b and 8c. Local battery is supplied over conductors clamped under screws 80 and 34p.

While certain embodiments of my invention have been described and shown for the purpose of illustration it will be understood that modincations, adaptations, and alterations thereof occurring to one skilled in the art may be made within the scope of my invention as defined in the appended claims.

What is claimed is:

1. A group of components adapted for assem-' bly to form telephone subsets of diiferent types comprising an open sided housing 0! a first shape having a cradle attached thereto in a first position relative to the open side and having. an opening adjacent said cradle, an open sided housing of a second shapehaving a cradle attached thereto in a second position relative to the open side and having an opening adjacent said cradle, a plurality of components united independently of said housings into a self-supporting assembly shaped to be housed in either of said housings and having a base portion shaped to substantially close the open side thereof, said assembly including a switch operating member and a switch adapted to be actuated by said member, and said assembly also including means for adjustably supporting said member in operative relation to said switch in either of two positions corresponding respectively to the positions of the openings in said first and second types of housing. a

2. A telephone subset comprising a base, a pair of contacts, a switching member for opening said contacts responsive to depression of said member, adjustable supporting means attached to said base for supporting said member movably in cooperative relationto said contacts in any of a plurality of determined positions relative to said base, a handset electrically connected to said contacts, a removable housing enclosing said contacts and said means, a cradle supported from said housing and adapted to receive said handset, said cradle being so disposed with respect to said member that in response to placement of said handset on said cradle said member is depressed by said handset.

3. A subset according to claim 2, further comprising'a cross connecting block having terminals and having conductive connections between said terminals, said contacts being attached to said block.

4. A subset according to claim 2, further comprising a transparent dust excluding cover substantially covering said contacts whereby the latter are protected from dust independent of said housing.

5. A telephone subset comprising a base, an outer housing attached to said base, a pair of contacts disposed in said housing but supported from said base independently of said housing,'an inner housing disposed around said contacts within said outer housing to protect said contacts from dirt independently of said outer housing, and actuating means operable from the outside of said outer housing for opening said contacts. L

6. A subset according to'ciaim 5 further comprising means for supporting said actuating means from said base independently of said outer housing.

7. A subset according to claim 5 wherein at least a portion of said inner housing is transparent.

ERNEST S. MCLARN. 

